Passenger&#39;s weight measurement device for vehicle seat

ABSTRACT

An upper rail is movable in a rear and front direction with respect to a lower rail fixed to a vehicle floor. A load sensor is fixed to an upper surface of the upper rail  4 , and a rectangular frame  30  is attached onto the load sensor. A rod of the load sensor sequentially penetrates a web of the rectangular frame, a plain washer and a spring holder upward, and a coil spring is wound around the rod. A bush is fitted to an edge of a hole of the plain washer, and a step difference is formed between an upper surface of the plain washer and the bush. A nut is screwed to the rod, and the nut tightens a bottom of a cup portion of the spring holder. In such a way, the coil spring is sandwiched between the spring holder and the web and is compressed, and an end portion of the coil spring engages with the step difference.

TECHNICAL FIELD

The present invention relates to a passenger's weight measurement devicefor a vehicle seat, which measures a weight of a passenger seated on thevehicle seat, and to an attachment structure for attaching a load sensorto the passenger's weight measurement device.

BACKGROUND ART

In recent years, in some cases, operations of various safety devicessuch as a seat belt and an air bag have been controlled in accordancewith a weight of a passenger seated on a vehicle seat for the purpose ofenhancing performance of the safety devices. In a conventionalpassenger's weight measurement device that measures the weight of theseated passenger, a load sensor is interposed between a vehicle floorand the vehicle seat (for example, refer to Patent Document 1 and PatentDocument 2).

-   Patent Document 1: JP A H8-164039-   Patent Document 2: JP A H9-207638

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

However, there is a dimension error or an assembling position error whenthe passenger's weight measurement device is assembled, when the vehicleseat is fixed to the passenger's weight measurement device or when thepassenger's weight measurement device is fixed to the vehicle floor, orthe like. Accordingly, it has been difficult to assemble the passenger'sweight measurement device.

In this connection, it is an object of the present invention to providea passenger's weight measurement device for a vehicle seat, which ismore easily assembled.

Means for Solving the Problems

In order to solve the above-described problem, a passenger's weightmeasurement device for a vehicle seat according to the present inventioncomprises: an upper rail provided on a lower rail fixed to a vehiclefloor so as to be movable in a rear and front direction; a load sensorfixed onto the upper rail; and a frame provided on the load sensor andbelow the vehicle seat, wherein a rod is extended from the load sensor,and the rod sequentially penetrates the frame, a plain washer and aspring holder, and is inserted into a coil spring, a bush is disposedalong an edge of a hole of the plain washer, though which the rod isinserted, and a step difference is formed between an upper surface ofthe plain washer and the bush by protruding the bush from the uppersurface, and a nut is screwed to the rod from above the spring holder,and the coil spring is sandwiched between the spring holder and theframe and is compressed and an end portion of the coil spring engageswith the step difference by tightening the nut to the spring holder.

Effect of the Invention

In accordance with the present invention, the frame can be shifted inthe vertical direction with respect to the load sensor. Accordingly,even if the lower rail, the upper rail, the frame and the like aredistorted during the assembling or the like, an initial load generatedby such distortions can be prevented from being applied to the loadsensor.

Moreover, the coil spring is sandwiched between the frame and the springholder in a state of being compressed by tightening the nut.Accordingly, the load sensor is fixed to the frame more stably andappropriately. Therefore, it becomes easier to assemble the passenger'sweight measurement device.

Furthermore, the load is stably applied from the coil spring to the nutowing to elastic deformation of the coil spring, which is caused bytightening the nut.

Moreover, by tightening the nut, the end portion of the coil springengages with the step difference formed between the upper surface of thewasher and the bush. Accordingly, the coil spring is centered withrespect to the washer without slipping on the upper surface of thewasher.

BRIEF DESCRIPTION OF THE DRAWINGS

This is a perspective diagram of a Passenger's weight measurement device1 for a vehicle seat.

[FIG. 2] This is an exploded perspective diagram of the passenger'sweight measurement device 1.

[FIG. 3] This is a perspective diagram of a load sensor 21.

[FIG. 4] This is a plan diagram of a rectangular frame 30.

[FIG. 5] This is a plan diagram of a right front portion of therectangular frame 30.

[FIG. 6] This is a cross-sectional diagram showing a cross section alonga line VI-VI of FIG. 5.

[FIG. 7] This is a cross-sectional diagram showing a cross section alonga line VII-VII of FIG. 5.

BEST MODE FOR CARRYING OUT THE INVENTION

A best mode for carrying out the present invention will be describedbelow by using the drawings. On embodiments to be described below, avariety of technically preferable limitations are imposed in order tocarry out the present invention; however, the scope of the invention isnot limited to the following embodiment and illustrated examples.

FIG. 1 is a perspective diagram of a Passenger's weight measurementdevice 1 for a vehicle seat, and FIG. 2 is an exploded perspectivediagram of the passenger's weight measurement device 1.

As shown in FIG. 1 and FIG. 2, a slide adjuster 2 for adjusting aback-and-forth position of the vehicle seat is attached onto a floor ofa passenger' s room. The slide adjuster 2 includes a left and right pairof lower rails 3 provided in parallel to each other, a left and rightpair of upper rails 4 engaged with the lower rails 3 so as to be capableof sliding on the respective lower rails 3 in a rear and front directionwith respect to the lower rails 3, a lower bracket 5 fixed to lowersurfaces of the lower rails 3 by bolt/nut coupling or rivet coupling andbridged between the left and right lower rails 3, a lock mechanism 6 forlocking the upper rails 4 to the lower rails 3 and for releasing thelocking, brackets 7 attached onto front end portions of the lowersurfaces of the respective lower rails 3, and brackets 8 attached ontorear end portions of the lower surfaces of the respective lower rails 3.These brackets 7 and 8 are attached onto the vehicle floor, and thelower rails 3 are fixed to the vehicle floor.

Brackets 9 are fixed to middle positions of upper surfaces of therespective upper rails 4 in a rear and front direction by the bolt/nutcoupling or the rivet coupling. The brackets 9 are provided in a stateof being erected with respect to upper surfaces of the upper rails 4. Aright end portion of a submarine pipe 10 is welded to the brackets 9,and the submarine pipe 10 is bridged between the two left and rightbrackets 9.

A load sensor 21 is mounted on a front end portion of the upper surfaceof the right upper rail 4, and another load sensor 21 is mounted on arear end portion thereof. Also on the upper surface of the left upperrail 4, load sensors 21 are mounted on a front end portion and rear endportion thereof, respectively. When viewed from the above, these fourload sensors 21 are arranged so as to be apexes of a square or arectangle.

FIG. 3 is a perspective diagram of the load sensor 21. All of the loadsensors 21 are provided in a similar way. As shown in FIG. 3, the loadsensor 21 includes a columnar sensing portion 21 a that senses a load, aplate-like flange portion 21 b extending horizontally in a rear andfront direction from a lower end of the sensing portion 21 a, a rod 21 cextending upward from an upper end of the sensing portion 21 a, and aconnector 21 d extending from the sensing portion 21 a so as to beparallel to the flange portion 21 b. The rod 21 c is formed into a malescrew shape. Female screw-shaped circular holes 21 e and 21 f whichpenetrate the flange portion 21 b in the vertical direction are formedin front and rear portions of the flange portion 21 b, respectively. Thesensing portion 21 a incorporates a strain gauge therein, and the loadis converted into an electric signal by the strain gauge.

As shown in FIG. 2, the load sensor 21 is fixed to the right upper rail4. Specifically, a lower surface of the flange portion 21 b abuts on theupper surface of the upper rail 4, and two bolts 22 inserted through theupper rail 4 upward from below are screwed to the circular holes 21 eand 21 f, respectively. Therefore, the load sensor 21 is fixed. Notethat the load sensor 21 may be fixed to the upper rail 4 by fasteningnuts to the bolts 22 on the flange portion 21 b without forming anyscrew threads in the circular holes 21 e and 21 f.

Any load sensor 21 is fixed to the upper rails 4 as described above.However, with regard to the two load sensors 21 fixed to the rearportions thereof, the connectors 21 d are directed forward, and withregard to the two load sensors 21 fixed to the front portions thereof,the connectors 21 d are directed backward.

As shown in FIG. 1 and FIG. 2, the frame 30 having a rectangular frameshape is mounted on these four load sensors 21. FIG. 4 is a top diagramof the rectangular frame 30. As shown in FIG. 4, the rectangular frame30 is composed of a left and right pair of beams 31, a front beam 32,and a rear cross pipe 33.

Either of the beams 31 is a metal member having a U-shaped crosssection, and has a web 31 a, an inner flange 31 b, and an outer flange31 c. Attachment holes 31 d are formed in a front portion and a rearportion of the web 31 a, respectively.

The front beam 32 is a metal member having a U-shaped cross section, andhas a web 32 a, a front flange 32 b, and a rear flange 32 c. The frontbeam 32 is bridged between front end portions of the left and rightbeams 31, and is welded to these beams 31.

The cross pipe 33 is bridged between rear end portions of the left andright beams 31, and is welded to these beams 31.

The rods 21 c of the load sensors 21 are inserted into the respectiveattachment holes 21 d upward from below, and nuts 46 are screwed to therods 21 c. Therefore, the load sensors 21 are attached onto a rightfront portion, a right rear portion, a left front portion and a leftrear portion of the rectangular frame 30, respectively. Referring toFIG. 5 to FIG. 7, an attachment structure for attaching the right frontload sensor 21 onto the right front portion of the rectangular frame 30will be described. FIG. 5 is a plan diagram of the right front portionof the rectangular frame 30, FIG. 6 is a cross-sectional diagram showinga cross section along a line VI-VI, and FIG. 7 is a cross-sectionaldiagram showing a cross section along a line VII-VII. As shown in FIG. 5to FIG. 7, an annular bush 41 is fitted to an edge of the right frontattachment hole 31 d, and grease is applied on the bush 41. The bush 41is made of synthetic resin. Moreover, a stepped collar 42 composed of acylindrical portion 42 a and an annular plate-like flange portion 42 bformed on one end surface of the cylindrical portion 42 a is insertedthrough the attachment hole 31 d in an inside of the bush 41. Here, thecylindrical portion 42 a is inserted through the attachment hole 31 dupward from below, and the flange portion 42 b engages with a lowersurface of the web 31 a via the bush 41. Therefore, the stepped collar42 is not pulled out upward. Moreover, the cylindrical portion 42 aprotrudes from an upper surface of the web 31 a, and an upper endsurface of the cylindrical portion 42 a is located at a higher positionthan the upper surface of the web 31 a. Here, the cylindrical portion 42a is fitted to the bush 41, and there is no gap between the cylindricalportion 42 a and the bush 41.

The rod 21 c of the load sensor 21 is inserted through the steppedcollar 42 upward from below. An inner diameter of the stepped collar 42is designed to be slightly larger than a diameter of the rod 21 c, andby such designing, a dimension error and an attachment position errorare solved.

The nut 46 is screwed to the rod 21 c. A plain washer 43, a coil spring44 and a spring holder 45 are interposed between the upper surface ofthe web 31 a of the beam 31 and the nut 46. An annular bush 43 a isdisposed along an edge of a hole of the plain washer 43, and the edge ofthe hole of the plain washer 43 is sandwiched vertically by this bush.Therefore, the bush 43 a is fitted to the edge of the hole of the plainwasher 43. In such a way, the bush 43 a and the plain washer 43 areintegrated with each other. Moreover, the bush 43 a protrudes from anupper surface of the plain washer 43. Therefore, a step difference 43 bis formed on the upper surface of the plain washer 43 by the bush 43 a.Moreover, a lower surface of the plain washer 43 and a lower surface ofthe bush 43 a become flush with each other. Furthermore, the rod 21 c isinserted through the coil spring 44, the coil spring 44 is set in astate of being mounted on the plain washer 43 on a circumference of thebush 43 a, and an end portion of the coil spring 44 engages with thestep difference 43 b formed by the bush 43 a. Therefore, the coil spring44 is centered with respect to the plain washer 43. A portion of thecoil spring 44, which is brought into contact with the plain washer 43,is formed to be flat. The bush 43 a is made of synthetic resin, and atapping sound is prevented by the bush 43 a.

The spring holder 45 includes a cup portion 45 c in which a through holeis formed in a bottom 45 b, and an annular flange 45 a formed on anouter circumferential surface in an opening of the cup portion 45 c.Then, the rod 21 c penetrates through the through hole of the bottom 45b of the cup portion 45 c, the bottom 45 b of the cup portion 45 c isset in a state of being mounted on an end surface of the stepped collar42, and the cup portion 45 c is inserted into the coil spring 44.Moreover, the coil spring 44 and the plain washer 43 are set in a stateof being sandwiched between the flange 45 a of the spring holder 45 andthe web 31 a.

The nut 46 is screwed to the rod 21 c in a state of being inserted intothe cup portion 45 c, and by tightening the nut 46, the bottom 45 b ofthe cup portion 45 c is sandwiched between the nut 46 and the upper endsurface of the cylindrical portion 42 a, and the coil spring 44 and theplain washer 43 are sandwiched between the flange 45 a and the web 31 aof the beam 31. Moreover, since the coil spring 44 is compressed bytightening the nut 46, the load is applied to the nut 46, andaccordingly, the nut 46 is prevented from being loosened.

Like the right front load sensor 21, the left front, left rear and rightrear load sensors 21 are attached onto the left front, left rear andright rear attachment holes 31 d, respectively. In a state where thefour load sensors 21 are attached onto the rectangular frame 30, thesubmarine pipe 10 is located behind the front beam 32.

As shown in FIG. 1 and FIG. 2, side frames 51 are welded to the outerflanges 31 c of the left and right beams 31, respectively. These sideframes 51 are parts of a bottom frame of the vehicle seat.

From above, front portions of the side frames 51 are covered with a panframe 53, and the side frames 51 and the pan frame 53 are fixed to eachother by the bolt/nut coupling or the rivet coupling. A seat spring 54is bridged between the cross pipe 33 and the pan frame 53, a cushion ismounted on the pan frame 53 and the seat spring 54, and the cushion, thepan frame 53 and the side frames 51 are entirely covered with a cover.

A backrest frame is coupled to rear ends of the side frames 51, and iscapable of rising and falling by a reclining mechanism. Note that thebackrest frame and the cushion are not shown in order to make it easy toview the drawings.

In the passenger's weight measurement device 1 configured as describedabove, when a passenger is seated on a seat bottom, a weight of thepassenger is applied to the four load sensors 21 through the rectangularframe 30, and is converted into electric signals by these load sensors21.

Here, the load sensors 21 are attached between the upper rails 4 and therectangular frame 30, and the load sensors 21 move in a rear and frontdirection integrally with the vehicle seat. Accordingly, a load inputtedfrom the vehicle seat to the load sensors 21 can be always kept constantirrespective of position of the vehicle seat in a rear and frontdirection. Therefore, measuring accuracy of the passenger's weight canbe enhanced.

Moreover, the spring holder 45 is mounted on the upper end surface ofthe stepped collar 42, and the coil spring 44 is sandwiched between thespring holder 45 and the web 31 a by tightening the nut 46. Accordingly,the rectangular frame 30 can be shifted in the vertical direction withrespect to the load sensors 21. Therefore, noise of the load generatedby distortion of the slide adjuster 2 and the like becomes smaller.

Moreover, even if the rectangular frame 30 can be shifted in thevertical direction with respect to the load sensors 21, the coil springs44 are interposed between the nuts 46 and the webs 31 a, andaccordingly, the load sensors 21 can be fixed to the rectangular frame30 more stably and appropriately. Therefore, it becomes easier toassemble the passenger's weight measurement device 1.

Moreover, the load is stably applied from each of the coil springs 44 toeach of the nuts 46 owing to elastic deformation of the coil spring 44,which is caused by tightening the nut 46.

Moreover, the submarine pipe 10 is located behind the front beam 32, andaccordingly, when forward inertial force is applied to the passengerowing to a frontal collision or the like of the vehicle, buttocks of thepassenger seated on the vehicle seat are restrained by the submarinepipe 10. Therefore, a so-called submarine phenomenon in which thepassenger moves under a waist belt can be prevented.

Note that the present invention is not limited to the above-describedembodiment, and various improvements and design changes can be madewithin the scope without departing from the gist of the presentinvention.

INDUSTRIAL APPLICABILITY

As described above, the present invention can be widely used, forexample, for seats of an automobile, an electric train and othervehicles.

1. A vehicle seat, comprising: right and left upper rails, provided oncorresponding right and left lower rails that are fixable to a vehiclefloor, so as to be movable in a rear-and-front direction; at least oneload sensor being attached above one of the right and left upper rails;and a frame member for the vehicle seat, the frame member being providedabove the load sensors, wherein for the at least one load sensor: a rodis extended from the load sensor, and the rod penetrates the framemember and a holder for an elastic member, and is inserted into theelastic member, the elastic member is provided between the holder forthe elastic member and the frame member, the holder for the elasticmember comprises a position regulating portion capable of regulating aradial position of the elastic member, the load sensor comprises aconnector extending therefrom, and provided below a load sensorattachment portion of the frame member, at least a part of the connectoris provided at a position apart from a shaft center of the rod of theload sensor, the elastic member, the holder for the elastic member andthe frame member are disposed in a line parallel with the shaft line ofthe rod of the load sensor, and wherein, in a space for disposing theelastic member between the frame member and the holder for the elasticmember, a space enlarged portion that is enlarged in the direction ofthe shaft line of the rod of the load sensor is formed, and at least apast of the elastic member is disposed in the space enlarged portion. 2.The vehicle seat as claimed in claim 1, wherein the at least one loadsensor is attached above a front portion of the one of the right andleft upper rails, and wherein the connector extends rearwardly from theload sensor that is attached above the front portion of the one of theright and left upper rails, and a rear end portion of the connector isprovided at the position farther apart from the shaft center of the rodthan the outer peripheral part of the corresponding load sensorattachment portion of the frame member.
 3. The vehicle seat as claimedin claim 1, wherein the at least one load sensor is attached above arear portion of one of the right and left upper rails, and wherein theconnector extends frontwardly from the load sensor that is provided onthe rear portion of the one of the right and left upper rails, and afront end portion of the connector is provided at the position fartherapart from the shaft center of the rod than the outer peripheral part ofthe corresponding load sensor attachment portion of the frame member. 4.The vehicle seat as claimed in claim 1, wherein the at least one loadsensor is attached on a front portion of one of the right and left upperrails, and wherein the load sensor provided on the front portion of theone of the right and left upper rails comprises a front portionconnector that extends rearwardly from such load sensor, and wherein anadditional load sensor is attached on a rear portion of the one of theright and left upper rails, and wherein the additional load sensorprovided on the rear portion of the one of the right and left upperrails comprises a rear portion connector extending frontwardly from suchload sensor.
 5. The vehicle seat as claimed in claim 1, wherein a platemember that is a separate member from the one of the right and leftupper rails is provided to fix the at least one load sensor above theone of the right and left upper rails.
 6. The vehicle seat as claimed inclaim 5, wherein a plurality of holes are formed in the plate member forfixing the plate member to the one of the right and left upper rails,and the plurality of holes are arranged in the rear-and-front directionon the one of the right and left upper rails.
 7. The vehicle seat asclaimed in claim 5, wherein the at least one load sensor is directlyattached to the plate member.
 8. The vehicle seat as claimed in claim 1,wherein the load sensor attachment portion is provided on a frontportion of the frame member, and the vehicle seat further comprises aconnecting member for connecting between a front side of the framemember and a front side of another frame member and, wherein theconnecting member is provided at a position that is different from aposition of the connector in a vertical direction.
 9. The vehicle seatas claimed in claim 8, wherein at least one end portion of theconnecting member is narrower in the rear-and-front direction than theload sensor attachment portion, the one end portion that is narrowerbeing connected with the frame member and being provided at a higherposition than a surface to which the load sensor is attached.
 10. Thevehicle seat as claimed in claim 2, wherein the load sensor attachmentportion is provided on a front portion of the frame member, and thevehicle seat further comprises a connecting member for connectingbetween a front side of the frame member and a front side of anotherframe member, wherein at least a part of the connecting member isprovided in front of the rear end portion of the connector.
 11. Thevehicle seat as claimed in claim 10, wherein at least one end portion ofthe connecting member is narrower in the rear-and-front direction thanthe load sensor attachment portion, the one end portion that is narrowerbeing connected with the frame member and being provided above theconnector.
 12. The vehicle seat as claimed in claim 3, wherein a loadsensor attachment portion is provided on a rear portion of the framemember, and the vehicle seat further comprises a connecting member forconnecting between a rear side of the frame member and a rear side ofanother frame member, wherein the connecting member is provided behindthe front end portion of the connector.
 13. The vehicle seat as claimedin claim 1, wherein the load sensor attachment portion of the framemember comprises a projecting wall projecting upwardly, and theprojecting wall is provided so as to face to the holder for the elasticmember.
 14. The vehicle seat as claimed in claim 1, wherein the loadsensor attachment portion of the frame member comprises a projectingwall projecting upwardly, and the connector is disposed below theprojecting wall.
 15. The vehicle seat as claimed in claim 1, wherein theload sensor attachment portion of the frame member comprises aprojecting wall projecting upwardly, wherein the part of the connectorthat is provided at a position apart from the shaft center of the rod ofthe load sensor is an end portion of the connector, the connector isdisposed below the projecting wall, and the end portion of the connectorextends in a rear direction or in a front direction more than theprojecting wall.
 16. The vehicle seat as claimed in claim 1, wherein arear portion part of a front load sensor attachment portion of the framemember comprises the projecting wall projecting upwardly, the front loadsensor attachment portion being provided at a front portion of the framemember, wherein the end portion of the connector that is provided at aposition apart from the shaft center of the rod of the load sensor is arear end portion of the connector, and the rear end portion of theconnector extends in a rear direction more than the projecting wall. 17.The vehicle seat as claimed in claim 1, wherein a front portion part ofa rear load sensor attachment portion of the frame member comprises theprojecting wall projecting upwardly, the rear load sensor attachmentportion being provided at a rear portion of the frame member, whereinthe end portion of the connector is a front end portion of theconnector, and the front end portion of the connector extends in a frontdirection more than the projecting wall.
 18. The vehicle seat as claimedin claim 1, wherein a front load sensor attachment portion is providedon a front side of the frame member and a connecting member is providedso as to connect between a front portion of the frame member having thefront load sensor attachment portion and another frame member.
 19. Thevehicle seat as claimed in claim 1, wherein at least one end of aconnecting member for connecting the frame member to another framemember is provided on a position that is shifted from the rod of theload sensor in the rear-and-front direction.
 20. The vehicle seat asclaimed in claim 1, wherein a rear load sensor attachment portion isprovided on a rear side of the frame member, a connecting member isprovided so as to connect between a rear portion of the frame memberhaving the rear load sensor attachment portion and another frame member,and an end portion of the connector is forwardly extended toward aposition in which the connecting member does not exist, the rear portionof the frame member being rearward of the rear load sensor attachmentportion.
 21. The vehicle seat as claimed in claim 1, wherein an upwardprojecting wall projecting upwardly is provided on the load sensorattachment portion of the frame member so as to face the rod of the loadsensor.
 22. The vehicle seat as claimed in claim 1, wherein a projectingwall projecting in a vertical direction parallel to the shaft of the rodis provided on the load sensor attachment portion of the frame memberand the projecting wall is disposed across the load sensor attachmentportion from the connector.
 23. The vehicle seat as claimed in claim 1,wherein an upward projecting wall projecting upwardly is provided on theload sensor attachment portion of the frame member, the connector isdisposed below the projecting wall and the projecting wall is disposedacross the load sensor attachment portion from the connector.
 24. Thevehicle seat as claimed in claim 1, wherein the position regulatingportion is provided unitedly with the holder between the rod of the loadsensor and the elastic member.
 25. The vehicle seat as claimed in claim1, wherein at least a part of the load sensor is provided at a positionfarther from the shaft center of the rod than an outer peripheral partof each of the load sensor attachment portion of the frame member. 26.The vehicle seat as claimed in claim 1, wherein: the holder for theelastic member includes a first surface and a second surface beinglocated at different levels in the direction of the shaft line of therod, an area between the first surface and the second surface of theholder for the elastic member forms the space enlarged portion, and atleast a part of the elastic member is disposed in the space enlargedportion.
 27. The vehicle seat as claimed in claim 26, wherein at least apart of the area between the first surface and the second surfaceregulates a radial position of the elastic member.